1. Field of the Invention
The present invention relates to an engine starter/generator. More particularly, the present invention relates to a structure for providing connection between a rotor of an engine starter/generator and an engine output shaft.
2. Description of the Related Art
A typical conventional engine starter/generator is disclosed in Japanese Utility Model Public Disclosure (KOKAI) No. 60-162978 (1985). The conventional engine starter/generator generally comprises, as shown in FIG. 5, a rotor 3 including a first rotor member 1a and a second rotor member 1b connected to the first rotor member 1a by a ring 2, a field winding 5 wound around a field core 4 and an armature 6. The boss portion of the first rotor member 1a can be engaged with and disengaged from a crankshaft 8 through a first one-way clutch 7. A sun gear 9 is formed on the outer peripheral surface of the boss portion of the first rotor member 1a. The sun gear 9 is meshed with a plurality of planet gears 11 which are, in turn, supported on a carrier 10 bolted to the crankshaft 8. The planet gears 11 are also meshed with an internal gear 12. The internal gear 12 can be engaged with and disengaged from a retainer 14 through a second one-way clutch 15. The retainer 14 is rigidly secured to an engine body 13 by a bolt.
The conventional engine starter/generator operates as follows. In the engine starting mode, the speed of rotation of the rotor 3 is reduced through a speed reducer that comprises the planet gears 11, the internal gear 12, etc. (i.e., the second one-way clutch 15 is locked, depending upon the direction of rotation of the planet gears 11, to fix the internal gear 12 in position, causing the carrier 10 to rotate at a reduced speed). As a result, an adequate turning torque is transmitted to the crankshaft 8. At this time, the first one-way clutch 7 overruns or freewheels (i.e., in a disconnected state). After the engine has been started, the second one-way clutch 15 is unlocked whereby the speed reducer no longer acts on the rotor 3. On the other hand, the first one-way clutch 7 is locked so that the rotation of the crankshaft 8 is transmitted directly to the rotor 3 through the first one-way clutch 7. This arrangement prevents the rotor 3 from rotating at an excessive speed.
In the above-described conventional engine starter/generator, however, the two one-way clutches 7 and 15 and the planet gears 11, which constitute a speed reducer, are arranged radially in line with one another. This results in an increase in the radial dimension of the prior art system. Thus, the prior art system is hardly fit in the engine room of a vehicle.